25 April 2018, Volume 40 Issue 2
    

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  • Comparative studies of the glacier mass balance in Svalbard,High Asia and Alps
    HE Haidi, LI Zhongqin, YE Wanhua, LIANG Pengbin, MU Jianxin, ZHANG Mingjun
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 205-213. https://doi.org/10.7522/j.issn.1000-0240.2018.0024
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the data of glacier mass balance and equilibrium line altitude, the characteristics of glacier mass balance change and equilibrium line altitude spatial distribution in Svalbard (Arctic), High Asia and Alps were analyzed. The following conclusions can be drawn:(1) Recently, the glacier mass balance is negative frequently, with the maximum average annual negative mass balance in Alps, reaching to -907 mm, followed by Svalbard, -431 mm, and then in High Asia, reaching to -264 mm. (2) The annual amplitudes of the mass balance in Svalbard and High Asia are relatively low, with small annual variation. The annual changing amplitude of the glacier mass balance in Alps is higher, with large annual variation. The glacier mass balance in Svalbard tends to be positive, and that in High Asia and Alps tend to be negative. (3) The glacier equilibrium line altitude in the interior of Svalbard is higher than that in coast. The glacier equilibrium line altitude in High Asia shows a latitudinal zonality, a longitudinal zonality and a regional zonality. The glacier equilibrium line altitude in Alps is mainly controlled by altitude.
  • Analysis of the changes of glacier mass balances in different parts of the world from 1980 to 2011
    ZHANG Guofei, LI Xiangfei, LI Zhongqin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 214-222. https://doi.org/10.7522/j.issn.1000-0240.2018.0025
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    Most of the glaciers in the world are seriously retreating with the climate warming; mass balances of the glaciers show a serious mass loss and a negative balance tendency. In this paper, based on the new mass balance data published by the World Glacier Monitoring Service, the current status of the glaciers in the world is summarized and compared; the regional characteristics, the change process and the overall tendency of the glacier mass balance changes in different parts of the world, as well as the recent contribution of glacier mass balance to sea level rise, are analyzed. The results showed that the global glaciers had experienced an accelerating mass loss and accelerating shrink, and the average glacier thickness had thinned 14 m from 1980 to 2011; the Alps and the Pacific Coast Ranges were particularly vulnerable, where glaciers had thinned about 30 m in average; the average mass balance changing tendency of the glaciers in different parts of the world had basically consistence with the general global average tendency; the changes of mass balance had been characterized by typical latitudinal zonality. Temporally, the change process of the mass balance of global glaciers may be divided into fluctuating positive balance type, fluctuating negative balance type and continuous increasing negative balance type. However, as a whole, the general tendency is continuous increasing negative balance. As the global climate warming in the future, the global glaciers will continue to shrink, mass loss rate will be increasing, negative balance will be increasing. The contribution of glacier mass balance to sea level rise will be increasing. It is believed that global temperature rise will be basically in synchrony.
  • Temporal and spatial variations of the maximum frozen depth of seasonally frozen soil in Tibet from 1990 to 2014
    GAO Siru, ZENG Wenzhao, WU Qingbai, JIANG Guanli, ZHANG Zhongqiong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 223-230. https://doi.org/10.7522/j.issn.1000-0240.2018.0026
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    The maximum frozen depth is the major index of the change in seasonally frozen soil. It is also an important parameter for the engineering design, construction and operation in seasonal frozen soil regions. The maximum frozen depth of seasonal frozen soil in Tibet from 1990 to 2014 were calculated by Stefan's method. The temporal and spatial variations of the maximum frozen depth were analyzed. The results indicated that the spatial distribution of the maximum frozen depth in Tibet had the characteristics of vertical zonality, latitude zonality and regional regularity, which had basically decreased from northwest to southeast from 1990 to 2014. In the context of global warming, the maximum frozen depth had decreased from 1990 to 2014. The maximum frozen depth had a negative correlation with the annual mean temperature and annual precipitation; the maximum frost depth decreased with the increase of annual mean temperature and annual precipitation. Beside, the response of maximum frozen depth to annual mean temperature was more significant than that to annual precipitation.
  • Recent surface elevation changes of three representative glaciers in Ányêmaqên Mountains, source region of Yellow River
    JIANG Zongli, LIU Shiyin, GUO Wanqin, LI Jing, LONG Sichun, WANG Xin, WEI Junfeng, ZHANG Zhen, WU Kunpeng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 231-237. https://doi.org/10.7522/j.issn.1000-0240.2018.0027
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    Ányêmaqên Mountains is located in the eastern part of the Tibetan Plateau, where there are many glaciers. The glacier change has an important significant in glacier response to climate change and for glacier meltwater resource accessment. In this article, interferometry of TerraSAR-X/TanDEM-X with bistatic mode was employed to retrieve high resolution and high precision Digital Elevation Models (DEM). Elevation changes of three representative glaciers between 2000 to 2013 were calculated by differential methods with SRTM DEM covered. It was found that surface elevation of the three glaciers has decreased as a whole in recent 13 years. In the Weigele Dangxiong Glacier, the surface elevation has decreased (4.16±3.70) m in average, mostly near the terminus; the debris covered area has expanded; the surface elevation has increased in the middle part of the glacier tongue. In the Halong Glacier, surface elevation has decreased (8.73±3.70) m in average from terminus to accumulation zone. In the Yehelong Glacier, surface elevation has decreased (13.0±3.70) m in average. However, from terminus up to 1.6 km, the surface elevation has increased 25.0 m in average, then has decreased clearly in average up to 1.6 km along the main flow line. Comparison between glacier outline of Chinese Glacier Second Inventory and Lansat 7/8 image found that terminus of the Yehelong Glacier had advanced about 500 m, indicating a fast advance or surge between 2000 and 2009. Thus, the conclusion can be drawn that the glaciers in Ányêmaqên Mountains had retreated as a whole from 2000 through 2013 with some advances.
  • The global glacierized area: current situation and recent change, based on the Randolph Glacier Inventory (RGI 6.0) published in 2017
    MU Jianxin, LI Zhongqin, ZHANG Hui, LIANG Pengbin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 238-248. https://doi.org/10.7522/j.issn.1000-0240.2018.0028
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    Based on the Randolph Glacier Inventory (RGI 6.0) published in 2017, current situation and recent change of global glacierized area were analyzed with reference to the statistics of glacierized area change in 16 first-order glacier regions of RGI. The results show that there are 215 547 glaciers covering an area of 705 739 km2 all around the world (excluding the Antarctic and Greenland ice sheets), with an uncertainty of 4.2%. The number of glaciers with the area below 1 km2 reaches 170 610 and accounts for the majority part (79.15%) of glaciers in the world. Glaciers with area above 100 km2 are totaled as 387 241 km2 and constitute the main part (54.9%) of the world's glaciers. The 45.5% of total glacierized area is in Arctic regions (Arctic Canada North, Arctic Canada South, Greenland Periphery, Svalbard and Jan Mayen, and Russian Arctic) and 18.8% in Antarctica and Sub Antarctic Islands. Glacierized area in High Asia accounts for 13.8% and that in Alaska for 12.3%. The area-weighted shrinking rate of global glacier was 11.3% and the interpolated annual percentages of area changes (APAC) of global glacier has been 0.35% since 1960. There is a significant regional difference in the magnitude of the APAC of glacierized area, with a difference of more than 30 times between the fastest one in low latitudes area (2.28%) and the slowest one in Arctic Canada North area (0.07%). Owing to lack of multiple global glacier inventories for comparison, quantitative studies of global-scale glacier change will continue to be the focus in the future.
  • Spatial-temporal variation of snow cover in the Tianshan Mountains from 2001 to 2015, and its relation to temperature and precipitation
    QIN Yan, DING Jianli, ZHAO Qiudong, LIU Yongqiang, MA Yonggang, Muattar Saidi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 249-260. https://doi.org/10.7522/j.issn.1000-0240.2018.0029
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    In this study, the spatial and temporal variation of snow cover in the Tianshan Mountains and its relation to temperature and precipitation were analyzed by using linear tendency estimate and correlation analysis, based on the Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover, MODIS land surface temperature data and China Meteorological Forcing Dataset during 2001-2015. The results demonstrated that:(1) There was obvious difference in monthly distribution of the snow cover percentage (SCP) for different elevation zones; the annual distribution of snow cover percentage presented a unimodal pattern below 4 000 m and over 5 000 m altitude; the maximum and minimum snow cover percentages occurred in winter and summer below 4 000 m, while the maximum and minimum values appeared in summer and winter over 5 000 m, respectively; the seasonal cycle of snow cover percentage exhibited a bimodal distribution between 4 000 m and 5 000 m altitude, with a peak in spring and autumn; during 2001-2015, there was a slight decreasing trend in annual mean snow cover percentage in Tianshan Mountains. However, there were differences in change trend of snow cover percentage in various seasons:there was a slight increasing trend in autumn, while a decreasing trend had been found in other seasons with more obvious in winter and summer. (2) The snow cover frequency (SCF) presented a spatial pattern from west high to east low and north high to south low due to water vapor sources and topography, and showed a positive correlation with elevation; the SCF had showed a decreasing trend during 2001-2015 in the Tianshan Mountains with more obvious in the altitude range between 3 600 m and 4 600 m. (3) In spring and summer, the temperature was the main cause of the change of snow cover percentage, and showed a negative correlation with snow; while in autumn and winter, precipitation was the main cause of the snow change, and had a positive correlation with snow. (4) Overall, the snow cover frequency showed a negative correlation with annual mean temperature and a positive correlation with precipitation; although there were great spatial differences in the degree of correlation and the significance level, the impact of temperature was larger than that of precipitation on SCF change.
  • Analyzing the spatial-temporal variations of snow depth in the Northeast China by means of remote sensing in consideration of frozen ground zonation
    LIU Shibo, ZANG Shuying, ZHANG Lijuan, NA Xiaodong, SUN Li, LI Miao, ZHANG Xiaowen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 261-269. https://doi.org/10.7522/j.issn.1000-0240.2018.0402
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    Snow cover is an important component of the cryosphere, which has an insulating effect on the ground. When snow melts, heat absorbing would reduce land surface temperature. Therefore, snow affects the growth of frozen ground, and is sensitive to climate change. Spatial and temporal variations of snow depth in frozen ground regions of Northeast China were analyzed by using spatial and statistics analysis function of GIS, based on the daily dataset of snow depth from 1979 to 2014. The results showed that the annual snow depth was 2.92 cm averaged from 1979 to 2014, with the maximum annual mean snow depth in the patchy permafrost regions and the minimum one in the seasonally frozen ground regions. Snow depth had decreased with the rate of 0.07 cm·(10a)-1, and the decreased area accounting for 39.77% of the total. The annual mean snow depth mutated in 1986 and then followed a decreasing, which was in accordance with the air temperature mutation. Affected by the terrain and the air temperature changing, the reduction of annual mean snow depth and the sensitive range mainly appeared in the patchy permafrost regions. Air temperature is main controlling factor to the annual mean snow depth in Northeast China. Precipitation, wind speed, humidity and sunshine duration can also influence the depth of snow cover. The snow depth in seasonally frozen ground regions is more sensitive than that in permafrost regions.
  • An analysis of air temperature evolution and its future trend in Heilongjiang Province
    GAO Yuzhong, WANG Chengwei, WANG Ji, HU Wendong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 270-278. https://doi.org/10.7522/j.issn.1000-0240.2018.0031
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    Using the annual mean and monthly mean air temperature data from 1961 to 2015 in Heilongjiang Province, a study was conducted on mean air temperature of the whole year, cold and warm seasons. The results showed that the interannual variation of air temperature in cold season had changed more and that in warm season had changed less. It is consistent with most other parts of China, that is, a relative colder period and a warmer period that lasted approximately 20-30 years in Heilongjiang Province under the background of unanimous warming trend in last century, while the criteria of colder and warmer periods were defined as follows:in a cycle of cold-warm, a warmer (colder) period is the continuous year that the average anomaly > 0℃ (< 0℃). If there is a reverse anomaly in a colder or warmer period, the lasting time should be ≤ 2 years. It is notable that if there is a climate trend of positive (negative) anomaly ≥ 4 years, even anomaly is negative (positive), it must be defined as a warmer (colder) period. As for the beginning and ending years of the warmer and colder period, they must depend on the climate trend, or it is a stable turning year that anomaly >3 years. In the light of the criteria here above, the mutation years of periods was:1964 from warmer to colder, 1988 from colder to warmer, 2009 from warmer to colder for cold season and the whole year. While 1969 from warmer to colder, 1996 from colder to warmer and around 2015 from warmer to colder. In the periods of warmer and colder, the interannual variations are relatively small and the climate trends in colder periods are higher than those in warmer periods. There are slight differences between the beginning and ending times for warmer and colder periods, and those of warmer period lag behind of those of colder period about 6 years. Interannual variation of air temperature is more in cold season than that in warm season. It is showed that a cold season entered colder period in 2009 and a warm season entered (or turning into) colder period around 2015. By using the LMDZ4 model and periodic statistics, the warm (cold) season air temperature was projected and discussed during 2016-2030 in Heilongjiang Province. Though the results of the two methods are not completely consistent, it is shown that the phenomenon of warming may be slowed down or even stagnated, a relatively colder period more likely be found in Heilongjiang Province.
  • Simulation of the impact of vegetation and soil characteristics on permafrost over the Tibetan Plateau based on the Noah land surface model
    WU Xiaobo, NAN Zhuotong, WANG Weizhen, ZHAO Lin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 279-287. https://doi.org/10.7522/j.issn.1000-0240.2018.0032
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    The sparse vegetation and coarse soils are widely distributed on the Tibetan Plateau. In this study, the impacts of vegetation and soil characteristics on permafrost distribution were simulated, as well as the key characteristics including active layer thickness and mean annual ground temperature on the entire plateau, based on the Noah land surface model (LSM). The simulation results were assessed by comparing with field survey data. The results showed that the Noah LSM, taking the sparse vegetation and coarse soil into account, is capable of modelling permafrost over the plateau. The permafrost area was reduced from 1.216×106 km2 to 1.113×106 km2 after considering the impacts of sparse vegetation and coarse soils. The simulated spatial differences mainly appeared in the transitional areas between permafrost and seasonally frozen soil and the patchy permafrost areas in the southern part of the plateau. The simulated active layer thickness averaged over the plateau and mean annual ground temperature were increased from 2.55 m to 2.92 m and from -2.17℃ to -1.65℃, respectively. These results indicate that the sparse vegetation and coarse soils have great impact on permafrost over the plateau.
  • Characteristics analysis of the cloud-to-ground lightning in Qinghai Province during 2008-2016
    TAO Shiyin, CAI Zhongzhou, WANG Min, HU Yan'an, JIN Xin, LUO Shaohui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 288-297. https://doi.org/10.7522/j.issn.1000-0240.2018.0033
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    To recognize the characteristics of lightning in Qinghai Province based on the cloud-to-ground lightning data collected from 2008 to 2016, the characteristics of cloud-to-ground lightning were analyzed by statistical approach in this article. It was revealed that there was an increase trend from 2008 to 2016 in Qinghai Plateau, the annual positive lightning ratio had been in between 10.1% and 19.8% with an average of 15%, and the percentage in spring and autumn had been higher than that in summer observably. The annual average total cloud-to-ground lightning intensity was 30.3 kA, including the average of positive lightning intensity of 50.1 kA and the average of negative lightning intensity of 27.2 kA. The gradient of cloud-to-ground lightning was 7.3 kA·us-1 in average, and 7.8 kA·us-1 for positive lightning and 7.2 kA·us-1 for negative lightning. The cloud-to-ground lighting frequency during summer (June-August) had been very frequent, accounting for 81%, followed by that in autumn (September-November), accounting for 13.5%. Daily variation of cloud-to-ground lightning had showed a single peak and single valley. The annual mean maximum cloud-to-lighting density was 10.4 times per square kilometer per year with an annual maximum positive cloud-to-lighting density of 2.1 times per square kilometer per year and an annual maximum negative cloud-to-lighting density of 2.1 times per square kilometer per year. Spatially, the high-value center of total cloud-to-lightning and negative cloud-to-lightning were in Xining, Datong and Huangzhong, while the high-value center of positive cloud-to-lightning was in Maqin and Tongde.
  • Permafrost degradation in Northeast China and its environmental effects: present situation and prospect
    CHEN Shanshan, ZANG Shuying, SUN Li
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 298-306. https://doi.org/10.7522/j.issn.1000-0240.2018.0034
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    Permafrost in northern part of Northeast China developed at high latitudes is very sensitive to climate change. Numerical simulations indicate that air temperature in the permafrost regions of Northeast China will continue to rise in the 21st century. Significant warming leads to degradation of permafrost. Northeast China has been warming since the 1950s. The warming trend of Da and Xiao Xing'anling Mountains is most obvious. Permafrost in the Northeast China presents the trend of regional degeneration from south to north. Permafrost degradation in southern part shows:(1) permafrost southern boundary is moving northwards, (2) the permafrost talik is enlarging, (3) the permafrost vanish gradually. Permafrost degradation in northern part of Northeast China shows:(1) permafrost base is moving upwards, (2) the thickness of active layer is increasing and the ground temperature is rising. The permafrost degradation leads to the deterioration of ecological environment in the cold regions. As a result, the belt of natural forests, dominated by Larix gmelinii, has shifted northward and wetlands have shrunk extensively, among many others. With rapid retreating and thinning of permafrost, large carbon pools sequestered in permafrost could be released to increase net sources of atmospheric carbon, creating a positive feedback, accelerating warming and influencing the global carbon cycle. Subsequently, permafrost degradation causes difference in thermal stability of permafrost and thus cause damage to engineered infrastructures in the cold regions. In addition, it affects microbes in permafrost, carbon cycle, along with ecology and hydrology in the cold region, etc., which are important factors of regional climate change and will be the focus of future research. The long-term fundamental data are the foundation of these research. Therefore, researchers need to further refine the permafrost parameters monitoring network, to clarify the relationships between climate change and permafrost degradation, and for evaluating the environmental effects of permafrost degradation.
  • Study on the frost heaving characteristics of fine sand with high salinity in northern Qinghai
    WU Yaping, WANG Ning, PAN Gaofeng, LI Tao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 307-313. https://doi.org/10.7522/j.issn.1000-0240.2018.0035
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    In order to investigate the influence of salt content and water content on the frost heaving properties of saturated fine sand with high salinity, to provide theoretical basis and reference for the design and construction of roads in the high salt content areas, an experimental study on the frost heaving properties of high salt saturated fine sand was carried out by applying frost heaving test under conditions of different water contents and different salt contents. Analyzing the influences of water content and salt content on frost heaving properties of sand specimens, it was found that the water content has little influence on the frost heave starting temperature of the salt sand, and the frost heave starting temperature mainly depends on salt content. When the salt content is 5%, the frost heave starting temperature is the highest, and then decreases with the increase of salt content. The frost heave rate increases with decreasing of temperature. Under the same salt content, the frost heaving ratio increases with increasing of water content in "S" type. When the salt content is less than 5%, the frost heaving ratio will increase with the increase of salt content. When the salt content is more than 5%, the frost heave rate will decrease slowly with the increase of salt content. Frost heave rate varying with water content and salt content can be described by a polynomial.
  • Optimization and validation of the soil heat flux parameterization scheme in permafrost regions along the Qinghai-Tibet Highway
    DU Yizhen, LI Ren, WU Tonghua, XIE Changwei, XIAO Yao, HU Guojie, BAI Rui, SHI Jianzong, QIAO Yongping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 314-321. https://doi.org/10.7522/j.issn.1000-0240.2018.0036
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    Soil heat flux acts as a key role in the surface energy balance, so it is also essential for the calculation and simulation of surface energy balance. Based on the climatology calculation scheme from Weng Duming, a soil heat flux calculation scheme was optimized using soil temperature, moisture and heat flux data along the Qinghai Tibet Highway. Independent data test results showed that compared with original scheme results, the reliability of optimized scheme has been greatly improved. The root mean square error in the Tangula and Xidatan sites had reduced 3.229 W·m-2 and 4.821 W·m-2, respectively, and the relative error had reduced 61.9% and 36.1%, respectively, so the new scheme can be used to effectively calculate local soil heat flux at the depth of 5 cm. In addition, the optimized scheme was used to simulate soil heat flux at the depth of 5 cm of 11 sites along the Qinghai Tibet Highway, the results showed that the soil heat flux at this depth presented an increasing trend, with a rate of nearly 1 W·m-2 during the past decade. Moreover, the annual average soil heat flux values in all sites were not less than 0.0 W·m-2, which indicated that local heat had a surplus at the yearly scale. The surplus heat could be used to heat the shallow soils, causing active layer thickness to increase significantly; when the soil heat flux increases 1.0 W·m-2, active layer thickness will increase 21 cm or so.
  • Bias characteristics of land surface model (CLM4.5) over the Tibetan Plateau during soil freezing-thawing period and its causes
    LI Shiyue, YANG Kai, WANG Chenghai
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 322-334. https://doi.org/10.7522/j.issn.1000-0240.2018.0037
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    The offline simulation experiments over the Tibetan Plateau was conducted through CLM4.5 (Community Land Model version 4.5) forced by China Meteorological Forcing Dataset. The observations in three sites (D66, TTH and Maqu) were chosen. The CLM4.5 simulation was compared to the observation and GLDAS (Global Land Data Assimilation System)-CLM2 simulation to analyze the biases of land surface model in simulating soil temperature and moisture during freezing-thawing process and its possible causes. The results showed that simulated soil temperature of CLM4.5 generally agreed with the observation (averaged RMSE ≈3℃), while soil temperature of GLDAS-CLM2 was higher than the observation with the biases (averaged RMSE >6℃) larger than that in CLM4.5, especially in freezing-thawing period; CLM4.5 can reproduce the seasonal variation of soil moisture, but content of soil moisture had some differences from the observation (averaged RMSE≈0.1 mm3·mm-3); GLDAS-CLM2 cannot reproduce the seasonal variation of soil moisture. The biases of CLM4.5 simulation mainly come from the uncertainties of atmospheric forcing, while the biases of GLDAS-CLM2 mainly come from the imperfection of frozen soil parameterizations, besides the uncertainties of atmospheric forcing. Air temperature and precipitation in atmospheric forcing have different effects on the performance of land surface model in freezing-thawing period and non-freezing-thawing period. In non-freezing-thawing period, simulation of soil temperature is mainly affected by the air temperature (r >0.6), especially before freezing period, the contribution of air temperature biases to soil temperature biases is larger than 50%, the variation of soil moisture is mainly influenced by precipitation, the contribution of precipitation biases to soil moisture biases is about 20%-40%. In freezing-thawing period, soil water flow and heat flux are coupled, the effects of air temperature and precipitation on soil temperature and moisture have reduced, the variation of soil moisture is significantly influenced by air temperature; contribution of air temperature biases to soil moisture biases is 10%-20%. The imperfection of freezing-thawing parameterization schemes in land surface model is the main factor for simulation biases of soil temperature and moisture during freezing-thawing; its effects are larger than the impacts of atmospheric forcing.
  • Simulation of seasonally frozen soil temperature based on the Snow Thermal Model (SNTHERM) in Northeast China
    LIANG Shuang, YANG Guodong, LI Xiaofeng, ZHAO Kai, JIANG Tao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 335-345. https://doi.org/10.7522/j.issn.1000-0240.2018.0401
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    Soil temperature has a major impact on soil fertility, plantation overwintering and microbial activities. Snow cover has albedo and insulation effect which will affect soil temperature and its freeze-thaw cycling in winter, and thus studying the impact of snow cover on soil temperature through effective model simulation is of great importance in the context of global change. The Snow Thermal Model (SNTHERM) is a one-dimensional heat and mass transfer model, which is able to predict temperature profile within snow cover and frozen soil. In this paper, the model combined with the dynamic observation of frozen soil temperature, adopted the statistical parameters and Nash-Sutcliffe efficiency coefficient, is applied to assess the accuracy and efficiency of the simulation of temperature change process of freezing-thawing soil under snow cover. The results showed that SNTHERM is able to simulate effectively the changing process of daily mean soil temperature at the depths of 5, 10, 15 cm under the snow cover with good agreement. The study revealed that the model having a good applicability under snow cover, which has improved the inversion accuracy of snow parameters. It is also suggested that the simulated accuracy of the soil water content will affect the simulated accuracy of soil temperature without snow cover, which reveals that considering the liquid movement in the model could improve the simulating accuracy.
  • Sensitivity analysis of the factors affecting the volumetric deformation of frozen sandy soil
    GAO Juan, LIAO Mengke, CHANG Dan, BAI Ruiqiang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 346-354. https://doi.org/10.7522/j.issn.1000-0240.2018.0039
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    In order to analyze the sensitivity of the factors affecting volumetric strain of frozen sandy soil, six internal and external affecting factors have been selected in this paper. According to the method of orthogonal experiment design, using the sandy soil from Delingha of Qinghai Province, a number of triaxial compression tests were conducted. The results were analyzed by using the grey relational analysis (GRA), the magnitude of the sensitivity of all the selected influencing factors and the sequence of them was given. The results showed that the sensitivity of water content, loading rate and temperature are more than 70%, so these factors need to be considered during the later experiments. With small water content, the volumetric strain of frozen sandy soil shows contraction first and then expansion; the axial strains corresponding to the peak stress and the peak strain are basically the same, while in saturated condition, the volumetric strain only shows volume expansion; the major influence of loading rate on frozen sandy soil was the change of the mechanical properties and failure forms. With the increase of loading rate, the amount of volumetric strain decreases, tangent modulus and peak strength increase, while the peak strain shows a decreasing tendency, the properties of frozen sandy soil approach brittleness. When temperature decreases, the cohesive force between particles increases and the pore pressure transforms into effective stress, which will increase strength and volume expansion. The results of this paper will be useful for optimal design of laboratory test and engineering application.
  • Study on the performance of gravel road stabilized by early strength agent and brucite fibers in alpine regions
    SHENG Yanping, LI Liangliang, GUAN Bowen, ZHOU Huili, HE Rui, CHEN Huaxin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 355-361. https://doi.org/10.7522/j.issn.1000-0240.2018.0040
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    Aiming to improve the adaptability of cement stabilized macadam base in the alpine regions, both early strength agent and brucite fiber were added to the basement layer. The performances, such as compressive strength, splitting tensile strength, shrinkage and frost resisting property of the base were studied. Also, the effect of adding brucite mineral fiber to cement-stabilized macadam was analyzed. Test results showed that after adding early strength agent and brucite fiber both, compressive strength and the splitting tensile strength of the base reached 85% after 3 days and reached 76% after 28 days, respectively, under curing at 20℃. Meanwhile, compressive strength and splitting tensile strength of the base in 3 days reached 69% and 68% in 28 days, respectively, under curing at -15℃. The anti-shrinkage properties of the base was improved by adding brucite fiber at the optimum mix amount of 4%, as a result, the dry shrinkage coefficient and shrinkage coefficient of the base were reduced by about 92% and 48%, respectively, compared to that without brucite fiber. Meanwhile, frost resistance of the base was improved as well, for example, when the optimum mix amount was also 4%, the BDR of the base would be 0.96%. Through the experiments, the following conclusion can be drawn:the addition of both early strength agent and brucite fiber in the base can not only improve the strength of the base but also prevent shrinkage and low temperature cracking. The optimum mix amount is 4% in the base.
  • Research progress of piles' thermostability in cold regions
    CHEN Hui, ZHANG Ze, FENG Wenjie, SHI Xiangyang, MING Jiao, DU Yuxia
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 362-369. https://doi.org/10.7522/j.issn.1000-0240.2018.0041
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    Due to a plenty of advantages, such as long anchorage length, deep burial, insensitivity to the changeable geothermal field and fast-refreezing, piles have been widely used in permafrost regions on the Tibetan Plateau. The study of piles' thermostability is always a comprehensive problem and it refers to many aspects, for instance, heat transfer theory, geocryology, design of piles, pile-soil interaction and so on. Based on lots of academic papers, the research progress of piles' thermostability by field and model tests and theorical calculation are summarized and analyzed in this paper. The following conclusions can be drawn:the soil refreezing procedure is affected by a lot of aspects, among which concrete hydration heat is the most significant; with the global warming, permafrost degradation will aggravate apparently on the Tibetan Plateau in the next 50 years, which threatens the piles' thermostability and corresponding protection measures need to be taken.
  • Annual variation of the runoff and precipitation in the Hulu River basin, a tributary of the Weihe River, from 1956 to 2016
    WANG Shuhong, ZHANG Yu, WANG Dachao, LU He, DU Lifang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 370-377. https://doi.org/10.7522/j.issn.1000-0240.2018.0042
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    It is of great significance for the regional water resources planning and exploitation to study the variation characteristics of river runoff and basin precipitation. In this paper, study was carried out of the variation of the Hulu River main runoff and basin precipitation, such as annual variation, periodic property and mutation, using the method of standard departure accumulation curve method, wavelet analysis and Mann-Kendall so on, according annual runoff data and precipitation data of the two main hydrological control stations on the upper reaches and downstream of the Hulu River. The result showed that the variation of runoff in the upstream and downstream of the Hulu River manifests good uniformity, and the annual variations of the Hulu River upstream and downstream runoff are basically identical. Both runoff and precipitation are decreasing, however, the rate of runoff reduction is far greater than that of precipitation and the decrease rate of downstream runoff is more than that of upstream. From the perspective of varying periodic, the main runoff change cycles in the Hulu River upstream and downstream are consistent. But in the downstream runoff transformation is more frequent than that in the upstream. The relationship between the upstream and downstream runoffs is not so good. The main cycle and subcycle of runoff are less than the change period of precipitation. Besides, runoff and basin precipitation change cycles show little corresponding relationship, and the varying cycle of runoff is short than that of precipitation. Finally, the runoff of downstream of the Hulu River had a obviously mutation in 1988, but there was no obvious abrupt changes in upstream runoff and in precipitation of the whole basin.
  • The dynamics of lakes in Mount Qomolangma Nature Reserve and their responses to regional climate change
    WANG Yi, LI Jingji, HAN Zijun, PENG Peihao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 378-387. https://doi.org/10.7522/j.issn.1000-0240.2018.0043
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    In this paper, object-oriented classification method was adopted to extract the lake information of Mount Qomolangma Nature Reserve by Landsat satellite images, and to analyze lake dynamics and the responses to regional climate change. The results showed:(1) Total lake area was 489.07 km2 in the Mount Qomolangma Nature Reserve in 2015, and tectonic lake, fluvial lake and glacial lake accounted for 77.3%, 2.6% and 20.1% of the total area, respectively. (2) During 1975-2015, the change rates of area were different for various kinds of lake in the reserve:glacier lake (1.05 km2·a-1) > tectonic lake (-0.85 km2·a-1) > fluvial lake (0.013 km2·a-1), with the change rates of glacier lake on south slopes (0.53 km2·a-1) > that on north slopes (0.52 km2·a-1). (3) There were periodic changes for the response of tectonic lake and fluvial lake in the north slopes with regional climate. During 1975-2000, the climate in Mount Qomolangma region was in warm and wet. In 2000, the lake areas of tectonic lake and fluvial lake reached to peak values. The two kinds of lakes had increased 22.8 km2 totally. During 2000-2015, the regional climate had changed to warm and dry, and the lake areas of tectonic lake and fluvial lake had decreased. An area of 57.16 km2 had decreased totally. However, as the warming of regional climate, the total area of glacial lake had enlarged constantly. The glacial lake had increased 43.06 km2 in the reserve in the near 40 years. (4) The grey relational analysis (GRA) results indicated that annual extreme low temperature had the most significant influence on the tectonic lake area. Annual mean air temperature had dominant effects to glacial lake and annual mean humidity had the largest impact on fluvial lake. Compared with other climatic factors, precipitation has the smallest impact on the area of various kinds of lakes.
  • Effect evaluation of artificial precipitation in Altay Prefecture, Xinjiang
    LI Jianli, YU Ye, ZHAO Suping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 388-394. https://doi.org/10.7522/j.issn.1000-0240.2018.0044
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    Effect of artificial precipitation was preliminarily evaluated in Altay Prefecture using daily precipitation data in seven weather stations from 1960 to 2015, and the dataset of surface hourly grid precipitation with the resolution of 0.1 degree in China from 2014 to 2015 provided by China Meteorological Data Service Center. The mean snowfall in winter had increased by 20.80 mm in the prefecture due to artificial snowfall. Furthermore, the percentage of snowfall in winter accounting for annual total precipitation had increased from 15.50% to 22.39%. The mean annual precipitation had increased by 39.47 mm, half of which was due to artificial snowfall, indicating significant effect of artificial snowfall. In addition, the mean rainfall in summer had increased by 16.59 mm in Altay Prefecture due to artificial rainfall with rain increasing rate of 4%, indicating that the effect of artificial snowfall in winter was more significant than artificial rainfall in summer.
  • Spatial and temporal distribution of virioplankton in arctic-alpine lakes
    SONG Xuanying, LIU Yongqin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 395-403. https://doi.org/10.7522/j.issn.1000-0240.2018.0045
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    Virioplankton is the most abundant component of planktonic microorganisms in lake, ranging typically from 105 to 108 mL-1, which plays an important role in aquatic ecosystem. Viruses modulate the abundance, productivity, composition and diversity of microbial communities through infection and lysis. The lytic processes of the host microbial cells infected by viruses can affect the biogeochemical cycle by releasing large amount of the cells into the lake water, altering the carbon cycle and nutrient transformation. The structures of lake ecosystem in arctic-alpine regions are simple. They are mainly dominated by microorganisms, so viruses may play an important role in microbial lives. However, there is scarce about current knowledge on viruses. In this paper, the recent advances in viral ecology of arctic and alpine lakes are reviewed, including the temporal and spatial distributions of virus abundance, the effects of biological and abiotic factors on viral abundance, the interactions between virus and hosts and the significant role of virus on carbon cycle and microbial loop in lake ecosystems. The virus is widely distributed with high diversity. Lysogeny is a survival strategy to escape unfavorable environments. Released organic carbon by viral lysis can affect microbial activity and loop. Based on the former studies, it is put forwards that how to research the virioplankton in the lakes of Tibetan Plateau.
  • Effect of return flows of third party in water rights transaction: a case study in Zhangye Prefecture
    WU Cuifang, XIONG Jinhui, DENG Xiaohong, YI Haiying, ZHANG Linling
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2018, 40(2): 404-414. https://doi.org/10.7522/j.issn.1000-0240.2018.0046
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    Water rights transaction is one of effective ways to improve the efficiency of water allocation and utilization. However, there is a severe challenge to the water right market due to the effect of return flows of third party. How to solve the problem of third party effect is the key to a perfect water market and to a higher efficiency of water use. In this paper, the scenarios of water transaction were designed, and the real effect of water rights transaction was estimated in Gan-Lin-Gao district of Zhangye Prefecture. Then a trading-ratio system was designed for water market to simulate the water right exchange rate and general water right trade with MATLAB simulation platform. Research results indicate that the effect of return flow during water right transaction within the agricultural sector is mainly affected by water amount. Taking the maximum tradable water amount as 30%, 50% and 80%, the water rights transaction between Yin'ke and Luotuocheng irrigation districts will result in return flows of third party of -5.97×106 m3, -9.95×106 m3 and -1.59×1011 m3 in Yanuan irrigation district, respectively; the greater the size of the market, the larger the return flows of third party. The total benefit of users under the water rights transaction ratio system is 1.09 billion RMB, which has increased by 0.34 billion RMB as compared with the initial state of allocation. The comparison shows that the water rights transaction ratio system can raise the efficiency of the water market and avoid the effect of return flows of third party simultaneously.
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